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A water rocket is a type of model rocket using water as its reaction mass. The pressure vessel (the engine of the rocket) is constructed from thin plastic or other non metallic materials (usually a used plastic soft drink bottle) weighing 1,500 grams or less. The water is forced out by compressed air. It is an example of Newton's third law of motion.

suggestions for cheap deployment trigger please?

Discussion about deployment systems including altimeters, timers, air speed flaps, servo systems, and chemical reactions.
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anachronist
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Re: suggestions for cheap deployment trigger please?

Post by anachronist » Thu Sep 20, 2018 10:11 pm

That buildig behind you looks like it's about to fall on top of you. :)



GrahamM
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Re: suggestions for cheap deployment trigger please?

Post by GrahamM » Wed Sep 26, 2018 4:37 am

Next flight day and much more successful.

Did 5 flights in all, pressures of 50, 80, 90, 100 and 100 psi and the nozzle held perfectly this time, so must have been poor preparation on the previous attempt.
The airflap deployment and nosecone worked perfectly but had mixed success with the parachute. Several flights opened properly, while some 'streamered' down or failed to unroll from the packed position.
Slo-mo of the launch
Launch and descent
The motorway in the second video is much more distant than the video makes it look. :)


Graham
Melbourne, Australia

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anachronist
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Re: suggestions for cheap deployment trigger please?

Post by anachronist » Wed Sep 26, 2018 10:19 am

A parachute shouldn't unroll. It should unfold. Look how skydivers fold their chutes. They don't roll it up, they fold it in an accordion zigzag fashion.

What I do is pinch the chute canopy in the middle and pull gently on the other end of the shroud lines. The parachute will naturally form folds like an umbrella. Then I lay this flat and make 3 or 4 zigzag folds perpendicular to the 'shaft' of the umbrella. You'll find that your parachute just wants to spring open. I don't wrap the shrouds around it, I sort of lay them down into the payload bay space and put the parachute packet on top. If it springs open a bit inside the bay, that's fine.



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